Appendix A: Glossary
AC See alternating current.
AC mains This is the type of current that is supplied to your house by the public utility companies. This is usually 120 volts AC and cycles back and forth 50–60 times per second.
AC signal This is the type of current usually picked up by a microphone or antenna. It has very low current and usually must be amplified before processing.
alternating current Current where the flow of current continually changes direction. This can also refer to a continual stream of fluctuations of voltage.
amp A shorthand way of saying ampere. See ampere.
ampere An ampere is a measurement of the movement of charge. It is equivalent to 1 coulomb of charge per second moving past a given point in a circuit.
amplification Taking a low-power signal and converting it to a high-power signal. This is usually done by using the low-power signal to control a high-power source and manipulate it to mimic the low-power signal.
AND function A logic function which yields a true value when all of its inputs are true.
AND gate A logic gate which implements the AND function.
anode An anode is the “positive side” of a polarized device. Note that, in batteries, the anode is actually the negative terminal (because the positive charge enters here).
Arduino A popular environment for programming microcontrollers, including a standard set of development boards for a variety of microcontrollers.
Arduino IDE A software program used to write and upload programs for Arduino-based microcontrollers.
atomic number The number of protons that a given element has.
auto-ranging multimeter A multimeter which does not require that you know the likely value of the measured value ahead of time.
baud A way of expressing rates of communication. Means “bits per second.”
beta The amount of gain that a BJT can generate.
bit Binary digit. A true or false (or 1 or 0) value.
BJT Bipolar junction transistor. In this type of transistor, current at the base of the transistor controls the conduction between the collector and the emitter.
boost converter See DC-DC power converter.
breadboard A device which makes it easier to attach components together. See also solderless breadboard.
breakdown voltage The voltage drop that occurs when a diode is blocking current, but the voltage goes beyond the capacity of the diode itself and “breaks down” the blockade. This is problematic in normal diodes, but an expected part of operation of Zener diodes.
bridge A space in the middle of a breadboard separating terminal strips.
brushed electric motor A motor that operates by changing its interior magnetic configuration based on wires that are rotating in the shaft.
brushless electric motor A motor that operates by changing its exterior magnetic configuration based on generating an alternating current inside the motor. Brushless motors are less prone to fail because of fewer parts that wear down.
capacitance Capacitance is the ability to hold an electric charge.
capacitative reactance The reactance that comes from capacitor-like components.
carrier frequency A frequency on which another signal is laid.
cathode A cathode is the “negative side” of a polarized device. Note that, in batteries, the cathode is actually the positive terminal (because the positive charge leaves here).
charge Charge is a fundamental quantity in physics. A particle can be positively charged (like a proton), negatively charged (like an electron), or neutrally charged (like a neutron). Charge is measured in coulombs.
chip See integrated circuit.
circuit diagram The drawing of a circuit using special symbols to show how the components are connected without worrying about how the circuit will be physically laid out on the breadboard.
circuit pattern A circuit pattern is a common way of building (and understanding) certain types of circuits or subcircuits.
closed circuit A circuit is closed if there is a complete pathway from the positive to the negative.
CMOS CMOS is a technology for building integrated circuits (especially MOSFETs) and stands for “Complementary Metal Oxide Semiconductor.” It is also a standard for true/false voltage levels used by logic chips made using CMOS technology.
coil See inductor.
comment In computer programming, a comment is a line of code that the computer ignores and is meant to communicate information to the person reading the code.
common point See ground.
common emitter A transistor circuit pattern where the emitter is tied to a known, fixed voltage.
connection point A place on a breadboard where a wire or component can be attached.
conserved quantity A quantity is conserved if, in the normal course of action, it cannot be created or destroyed. Energy is a conserved quantity—it cannot be created or destroyed but only transferred.
conventional current flow Conventional current flow traces the flow of positive charge in a circuit from a positive source (often a battery) to either ground or a negative terminal.
coulomb A coulomb is a quantity of electric charge. One coulomb is roughly equivalent to the charge of 6.242Œ1018 protons. The same number of electrons produces a charge of −1 coulomb. Coulombs are represented by the symbol C.
coupling capacitor A coupling capacitor is a capacitor that links to circuits, usually at different DC offsets. The coupling capacitor transmits changes in voltage (i.e., AC) while blocking the DC offset voltages from influencing each other.
datasheet The documentation provided by a component or an integrated circuit which provides technical details about the component’s operation.
debugging The process of finding errors in electronic circuits or computer code.
DC-DC power converter A device which converts voltage levels (like a transformer) but for DC circuits.
DC bias voltage See DC offset.
DC See direct current.
DC motor A device that converts DC electrical power into mechanical power.
DC offset If an alternating current is centered around a voltage other than zero, the center voltage is the DC offset.
depletion mode A FET which uses depletion mode means that the FET normally conducts between the drain and source, but will be inhibited by sufficient gate-to-source voltage (sufficiently positive for a P-channel or sufficiently negative for an N-channel).
development board A development board is a prebuilt circuit board that makes trying out certain chips and components (and building example projects with them) much easier.
digital logic A convention where voltages (usually a positive voltage and zero voltage) are used to represent “true” and “false” values (or “1” and “0”).
diode An electric component that only allows current to flow in one direction.
DIP See dual in-line package.
direct current Current where the flow of current maintains the same direction. It can also be viewed as steady voltage from a positive terminal to a negative terminal (i.e., voltage which does not continually vary/change directions).
dissipation Dissipation refers to the ability to get rid of something. Heat dissipation deals with the removal of extra heat generated in circuits.
drain (transistor) One side of the main current pathway of a FET. This is the positive side in an N-channel FET and the negative side in a P-channel FET.
dual in-line package A type of package for integrated circuits which has two parallel sets of pins which fits nicely across the bridge of a breadboard.
electric field This is the force of attraction of opposite charges which are separated but near to each other.
electromagnet A magnet that is created through an inductor. Electromagnets allow electronics to manipulate the larger physical world.
electron current flow Electron current flow traces the flow of negative charges from a negative source or ground to its destination (often a positive terminal on a battery).
electron A negatively charged particle that is usually on the outside of an atom.
energy The ability to do work, usually measured in joules.
enhancement mode A FET which uses enhancement mode means that the FET normally does not conduct between the drain and source, but sufficient gate-to-source voltage will allow conduction (sufficiently positive if it is an N-channel and sufficiently negative if it is a P-channel).
equivalent resistance If multiple resistors are connected in series or in parallel, their operation can be mimicked by a single resistor. This resistor is said to have equivalent resistance of the resistor circuit that it replaces. See also Thévenin equivalent circuit.
farad The basic unit of capacitance named after Michael Faraday.
feedback When the output of a process feeds back into the input of a process.
FET Field effect transistor. This is a type of transistor where the gate controls the conduction between the drain and the source.
filtering capacitor A capacitor used to remove signals of a certain range of frequencies from the signal.
flash memory A type of memory in integrated circuits that is retained even after the power to the device is removed.
flux See magnetic flux.
flyback diode See snubber diode.
forward voltage drop The amount of voltage that a diode utilizes when the current flows forward.
frequency How often a cycle of an oscillator completes a full cycle, measured in hertz (cycles per second).
function In computer programming, a function is a block of code that accomplishes a task and may return a value to the code that invoked the function.
gain The amount of amplification that a component provides to a signal.
gate (logic circuit) See logic gate.
gate (transistor) In a FET, the gate is the input that controls the pathway between the drain and the source using voltage levels. Gates generally utilize a negligible amount of current.
ground The chosen point on a circuit by which to measure other voltages. On DC battery circuits, this is usually simply the negative terminal of the battery.
H-Bridge A device which makes it easier to control a two-way motor drive.
headers Places on a circuit board where additional circuits or wires can be attached.
heat Undirected energy. In electronics, heat is usually due to inefficiency in circuits. All circuits are inefficient to some degree, and that inefficiency is released as heat into the environment.
heatsink A heatsink is an object, usually large and metallic, which attaches to a part of a circuit to dissipate heat into the environment and away from the circuit itself.
henry The unit of measure for inductance.
hertz A unit of measurement of frequency/oscillation. Abbreviated Hz. Hertz refers to the number of cycles per second.
IC See integrated circuit.
in-system programmer A device that connects your computer to a microcontroller which will transmit a new program to the microcontroller.
inductance The amount of resistance an inductor offers to changes in current. Measured in Henries.
inductive kick When current is suddenly blocked to an inductor, the magnetic field suddenly collapses and generates a sudden large voltage at the cathode.
inductive reactance The reactance that comes from inductor-like components.
inductor A component, usually made of coiled wire, that stores energy in a magnetic field. Inductors resist changes in current.
impedance The amount of resistance a circuit offers to alternating current which combines resistance and reactance. Impedance is usually based on a specific frequency.
inefficiency In energy terms, inefficiency is the amount of energy that is wasted in performing a process. All processes are inefficient to some degree.
integrated circuit A miniaturized circuit that is built on a silicon chip.
International System of Units See SI Units.
inverted input or output An input or output is inverted if you send it (or receive from it) the opposite of what you might normally expect.
ISP See in-system programmer.
joule A standard unit of work or energy. It is defined as the amount of work performed when a 1-kilogram object is moved 1 meter. It can also be defined as the work performed when moving a coulomb of charge through 1 volt of electric potential difference.
junction The point where two or more wires or components are connected together.
Kirchhoff’s current law At any junction, the total amount of current going into a junction is exactly the same as the total amount of current going out of that junction.
Kirchhoff’s voltage law Given any two specific points on a circuit (at a particular point in time), no matter what path is traveled to get from one point to the other, the difference in voltage between the two points is the same. This can also be stated equivalently as saying that any complete, closed path around a circuit has a total voltage drop of zero.
latch A simple type of memory that stores a single bit using logic gates.
lead A metallic connection point of a component.
leg See lead.
logic function A function that takes in one or more logic (true/false) values as input and produces one or more (usually one) logic values as output.
logic gate A circuit which implements a logic function. This is different from a transistor gate. Confusingly logic gates are built from transistors which can have a gate.
loop In computer programming, a loop is a group of commands that is repeated multiple times.
magnetic flux The energy stored in an electric field.
mechanical fit The ability of two objects to be joined just by pushing them together.
memory The capacity of a circuit to hold on to previous values. Often used in computer programming to store values.
microchip See integrated circuit.
microcontroller An integrated circuit which operates as a standalone computer. Usually used for controlling small electronic devices.
milliamp A short way of saying milliampere. See milliampere.
milliampere One thousandth of an ampere. See ampere.
MOSFET A specific (and common) type of FET transistor.
multimeter A device used to measure a variety of electrical quantities in circuits and devices, usually including voltage, current, and resistance.
N-channel A type of FET. Refers to the physical construction of the FET.
NAND function A logic function which yields a false value only when all of its inputs are true. A combination of the AND and NOT functions.
NAND gate A logic gate which implements the NAND function.
NPN A type of BJT.
neutron An uncharged particle in the nucleus of an atom.
no load RPM The speed at which the shaft of a motor rotates with nothing attached to the shaft at its rated voltage.
no load current The amount of current that a motor utilizes with nothing attached to the shaft at its rated voltage.
non-polarized component A circuit component (such as a resistor) where it does not matter which end is used as the anode or cathode.
NOR function A logic function which yields false if any of its inputs (or combination of inputs) are true. A combination of the OR and NOT functions.
NOR gate A logic gate which implements the NOR function.
NOT function A logic function which takes one input and yields its opposite.
NOT gate A logic gate which implements the NOT function.
nucleus The nucleus is the part of the atom where protons and neutrons reside.
ohm The unit of measurement of resistance.
open circuit An open circuit is a condition where there is no electrical pathway for the current to flow. See also closed circuit, short circuit.
open collector A type of output from a circuit where the “positive” state is actually disconnected, while the “zero” state is an actual ground voltage. This is often used to allow the user of the circuit to supply their own voltage through a pull-up resistor.
OR function A logic function which yields a true value when any of its inputs are true.
OR gate A logic gate which implements the OR function.
oscillation Oscillate means going back and forth. In electronics, oscillation usually means periodic back-and-forth fluctuations in current or voltage.
oscillator An oscillator is a circuit that switches back and forth between two or more states (e.g., positive voltage to zero voltage) in a regular fashion.
oscilloscope A device used to probe circuits and visualize the behavior of circuits over time.
P-channel A type of FET. Refers to the physical construction of the FET.
package The way that an integrated circuit is encased, including the physical casing, the pinout, and the type of pins.
parallel circuit A circuit is a parallel circuit if one or more components are arranged into multiple branches.
period The length of a full cycle of an oscillating circuit. Usually measured in seconds.
pad See pin.
pin On an integrated circuit, this is one of the legs protruding from the chip that you can connect to your circuit. Can also refer to the leg/lead of other types of components.
pinout The pinout refers to the meaning/purpose assigned to each pin of a particular integrated circuit.
PNP A type of BJT.
polarized component A circuit component (such as a diode) which has an explicit anode and cathode (i.e., the sides of the component are not interchangeable).
power The continual supply of energy, usually measured in watts. In DC circuits, power is calculated as the voltage (in volts) multiplied by the current (in amperes).
power buses See power rails.
power rails The part of a breadboard (usually indicated by red and blue lines) which is usually used for power connections.
power transistor A transistor made to handle large amounts of voltage and current.
programming environment A set of tools which makes programming for certain devices, or in certain ways, easier.
protection diode A diode that protects a circuit, usually either from putting in a battery backward or, in the case of a snubber diode, from inductive kick.
proton A positively charged particle in the nucleus of an atom.
pull-up resistor A resistor connected to a positive voltage which gives a default positive voltage if no other voltage is connected on the line.
pull-down resistor A resistor connected to a positive voltage which gives a default zero voltage if no other voltage is connected on the line.
pulse-width modulation Sending a signal using a fixed pulse frequency, but where the percentage of time the signal is high vs. low varies. This is a way of outputting voltage levels on devices that don’t support outputting at different voltage levels.
PWM See pulse-width modulation.
quiescent current In a transistor amplifier, the quiescent current is the amount of current that is flowing into the base of the transistor when no signal is applied.
RC circuit A resistor in series with a capacitor, usually used for timing.
reactance This is a part of impedance which is similar to resistance but operates by preventing flow rather than dissipating energy. Reactance is usually based on the frequency of the signal.
resistance Resistance measures how much a component resists the flow of electricity. Resistance is measured in ohms (Ω).
resonant frequency The resonant frequency of a circuit is the frequency of the circuit where the inductive and capacitative reactances cancel each other out.
RMS A way of computing averages that focuses on magnitudes.
RPM Revolutions per minute. How often the shaft of a motor rotates in a minute.
RS-232 A protocol for serial communication describing voltage levels, timing, and other important signaling features for sending and receiving bits using two wires.
saturation mode This occurs in a transistor when it is fully on and cannot amplify the signal further. In saturation mode, the transistor acts more like a switch that is on rather than as an amplifier.
schematic See circuit diagram.
serial interface A type of input/output mechanism that sends data a single bit at a time, oftentimes using the RS-232 protocol.
series circuit A series circuit is a circuit or part of a circuit where all of the components are connected one after another.
servo motor A motor that, instead of spinning, creates an angle.
set screw A screw whose purpose is to apply pressure to another part to join it together.
shaft The rotating part of a motor.
short circuit A short circuit is what happens when the current pathway has no resistance from the positive to the negative.
SI Units The international standard for physical units of measure.
sink When a component or circuit receives incoming current.
snubber diode A diode that is wired backward across the terminals of an inductor to protect the circuit against inductive kick.
solder (noun) A substance which can be heated up to attach wires, components, and other metallic objects together.
solder (verb) The activity of attaching things together using solder.
solderless breadboard A device consisting of a number of connected terminals where components can be inserted and removed at will, which allows for the construction of circuits in a nonpermanent way.
source (general) When a component or circuit provides current output.
source (transistor) One side of the main current pathway of a FET. This is the negative side in an N-channel FET and the positive side in a P-channel FET.
square wave An oscillating signal where the signal spends almost all of its time either in the high or low state and almost no time in between.
SR latch A simple type of memory which can store a single bit.
stall condition In an electric motor, this is the condition where the motor is not turning while it is exhibiting its maximum torque.
stall current The amount of current that the motor uses in a stall condition.
stator The fixed outside container of a motor.
terminal See lead. Can also refer to a female receiver for a lead.
terminal strip On a breadboard, a terminal strip is a row of connection points which are connected together within the breadboard, so that putting in multiple components or wires on a terminal strip connects them together.
Thévenin equivalent circuit A generalization of how one circuit “sees” another circuit, as if it solely consisted of a power source and an impedance/resistance.
TO-220 package A way of packaging an integrated circuit, usually for transistors, voltage regulators, or other power-oriented devices. It consists of three terminals and a heatsink.
torque Rotational power. In a motor, this is the amount of rotational power that the motor applies to the shaft.
transformer A pair of inductors which utilize the magnetic field in one coil to generate a current in the other inductor. Usually used to convert voltage levels in different circuits and to isolate parts of a circuit. Transformers only operate on AC circuits. For DC circuits, see DC-DC power converter.
transistor A circuit component used for switching, logic, and amplification. Generally, a transistor operates by having one terminal control the flow of current between two others. See also FET and BJT.
TTL An acronym for transistor-to-transistor Logic. This is an old standard for logic chips for signaling true and false values, usually operating at 5 V.
unit of measurement A standard marker used for quantification, such as grams (weight), seconds (time), or meters (length).
unit prefix A unit prefix is a modifier that can be added to a word to indicate that it should be multiplied by some amount. For instance, a kilometer means a thousand meters. A millimeter means a thousandth of a meter.
variable In computer programming, a variable is a storage location where a value is held that can change.
variable resistor A resistor whose value changes.
voltage A voltage is the “power” of an electric charge. Formally, it is the ratio of potential energy of a charge to the magnitude of a charge. It can also be described as the change in magnetic flux over time.
voltage divider A voltage divider occurs when there are two components (usually resistors) connected together with a terminal coming out from between them meant to have a voltage between that of the two components.
voltage drop The voltage difference between two points on a circuit. This usually refers to the amount of voltage consumed within a specific component on a circuit.
watt A unit of power. A watt is the delivery of one joule per second.
work Work occurs when force causes a displacement (change of position). Work is often measured in joules.
XOR function A logic function which yields a true value when any one (and only one) of its inputs is true.
XOR gate A logic gate which implements the XOR function.
Zener diode A diode which is meant to be wired in such a way as to take advantage of its breakdown voltage.
